Bottlehead line level tube buffer?

[SPaulMac]

I understand these are a bit smoke-and-mirrors, but any chance of Bottlehead producing a line level tube buffer a la the old Musical Fidelity X-10 units? I'm playing high bitrate files from a MacBook Pro via an HRT Music Streamer II into an all solid state system and it sure would be nice getting a bit of tube glow in there somewhere (the heat output of tubes being scientifically proven to provide the "warmth" of tube playback ;-) ). And if the answer were to be say, no, any possibility of modifying the Quickie circuit to act as such? Having finished all my kits, I'm having a little trouble letting go of DIY. :-)

[Grainger49]

I think that the Quickie would pass for the buffer.  It is a single stage, Pentode IIRC.

[Paul Joppa]

As near as I can tell, the old X-10 was a two-stage preamp with huge feedback to reduce the gain to nearly unity. Not something I'd expect to sound all that great, though tastes do vary.

[SPaulMac]

In all seriousness concerning the Quickie, it was more of an impulse buy rather than a necessity, so I'll probably press it into service between the Music Streamer and my preamp. I'll be interested to hear if it makes any difference either positive or negative.

My lack of knowledge of electronics would fill a nice set of encyclopedias, so this question my come across as a bit stupid, but having added a headphone output to the Quickie as a lark, is it possible this could effect the sound quality of the pre-amps output in some negative way? I understand the transformers were added after the outputs and I assume would have no effect, but it appears I could at worst add a switch to disconnect the input to the transformers if necessary.

[Paul Joppa]

Yes, the transformer is likely to remove some of the bass unless you spent the big bucks on a high-end transformer. Direct out with the transformer removed will have the best frequency response and lowest distortion.

[SPaulMac]

Thanks, Paul. I'll definitely be pulling the transformers out then.

[Wanderer]

Would think adding a "cut" switch, or two mono switches, to the Quickie to take the autoformers out of circuit would accomplish the same thing, then you could switch the headphones back in if you want to.

On the "tube buffer" idea it seems to be an attempt to add "tube-ish-ness" to a harsh sounding soild state rig.  IMHO the fix for a hard sounding hi-fi rig is selling it off and getting something that sounds good. Tossing a tube into a mediocre system is like covering a badly cooked steak in ketchup.

Again, IMHO, tubes don't make good "buffers", tubes for gain stages,  transformers or maybe FETs for buffers.

My opinion and "Mileage may vary" and all that.

Kevin R-M                

[Wanderer]

I just reread my previous post and strikes me my tone could be mis-interpeted .

I certainly DO NOT intend my comments as a dig at the OP or his audio system. My comments were intended "in general" about add on tube buffers like the MF X-10.

 Kevin R-M 

 

[Dr. Toobz]

Another idea is to make a few easy circuit changes to the Quickie to get a cathode follower circuit. I've tried it, if just for the theoretical exercise, by removing the C4S (or stock plate resistors), taking the plates right to the B+ (36VDC), and putting a 150H, 8mA Hammond choke under each cathode, in place of the cathode resistor. Then, the output is taken off the cathode vs. plates (through a coupling capacitor, as usual). Seemed to work well, though gain was certainly less than unity. (I think there's a way to actually use pentodes in a cathode follower circuit vs. triode wiring tem, which will take you closer to unity gain - but that's beyond my meager electrical knowledge as a psychologist!).  Microphonics were reduced, as was distortion, since a cathode follower topology is inherently low in distortion. This lead to better sounding highs and bass than the 3S4's in their usual configuration, which I've found to overload pretty easy from CD-level input, getting overly warm and thick sounding with a decreased soundstage.

Definitely give the OPT's the boot before anything! (Such as via a cut switch). A gigantic difference in my experience. The Quickie is definitely a great way to add another stage between devices, if you're into that sort of thing - with SS, I could see how that would help. SS often sounds overly dry or "damped" to me - nothing a little 2nd harmonic distortion won't cure.